6 ms·

The third option is that everything is simply too far apart and any detectible transmissions are either too faint or buried behind all those massive fusion furn

• thrashh 5y ago
  Another possibility is that energy is really hard to come by. Humans absolutely struggle to amass much energy. Think of the insane amount of energy required to lift things into space, and how many millions more amounts of energy we’ll need just to build something in space. Heck if you go drive off grid on Earth, you can barely bring any energy with you and you won’t really be able to generate an appreciative amount of energy to do anything major. Climate change is ultimately caused by our energy needs. One day we might be able to harness the output of a whole star but the amount of energy we’d need to get to that point seems out of reach right now. I wouldn’t be surprised if the lack of energy is a universal issue across the stars. A huge game changer would be if we discovered some physical phenomenon to allow us to safely extract energy easier from mass. It would do to our progress like what the telephones and the Internet did to communication.
  • pfdietz 5y ago
    It actually doesn't require THAT much energy to get into orbit. The energy of a kilogram of mass in low earth orbit is about 9 kWh, although rockets will use a bit more than that (not enormously more, though). Fuel cost remains a minor fraction of launch cost, even with Falcon 9. In comparison, the best aluminum plants in the world use 13 kWh to make a kilogram of aluminum. Yet no one says aluminum is out of reach because it takes too much energy to make it. The per capita primary energy consumption in the US is about 10 kw; your share of this energy over your lifespan would be enough to accelerate 1 kg to 2% of the speed of light.
    • shagie 5y ago
      An interesting problem is "how much energy would it take to launch from a super-earth?" https://www.space.com/40375-super-earth-exoplanets-hard-aliens-launch.html https://www.space.com/40375-super-earth-exoplanets-hard-alie... > To launch the equivalent of an Apollo moon mission, a rocket on a super-Earth would need to have a mass of about 440,000 tons (400,000 metric tons), due to fuel requirements, the study said. That's on the order of the mass of the Great Pyramid of Giza in Egypt. We may be in a Goldilocks zone not only for distance from the primary star (lots of systems are binary which gets problematic), but also in terms of size of the planet (not to light to loose atmosphere, not to heavy to trap everything), and we've got a nice big moon to keep things sloshing around and stabilize the tilt. I am of the opinion that life is rare because we live in a surprisingly boring solar system with a terrestrial planet in the right range, not to large and not too small, and with a massive moon.
      • pfdietz 5y ago
        A super earth would require exponentially more energy with chemical rockets, due to that darn rocket equation. Fortunately, Earth isn't that bad.
        • foobarian 5y ago
          > A super earth would require exponentially more Polynomially, right?
          • pfdietz 5y ago
            No, exponentially. I used that word precisely, because the mass ratio in the rocket equation is exponential in (delta V)/(exhaust velocity).
            • foobarian 5y ago
              Thanks for the reply. Context: there are so few exponential processes in nature, especially around classical physics that it really stuck out here, so I made the comment. I should have searched and read up on it instead, but thought there is still some value in others seeing the conversation. And lastly: that is really depressing :-(
  • vbezhenar 5y ago
    That's why it makes no sense to build something big by lifting heavy things from the Earth. Just mine asteroids, extract iron, melt it into chunks, then transport those chunks very slowly but with huge throughput from asteroids to the necessary building site in space and use them to build space ship. You can melt iron just by focusing enough sun light and you can build ships closer to sun for cheaper sun light. It's imaginable with current technologies, we just need industry to move into space. Imagine that with all your knowledge you suddenly moved to the ancient times. You know how to make CPU but you can't even make a shovel because iron production is not there. You need to spend enormous amount of time and efforts to build all the industries required to build a factory to produce simple resistor. That's where we at when it comes to space right now. We need to spend lots of time and effort to build space industry. But once it's there, space ships will not be a big deal.
    • pdfernhout 5y ago
      Thinking through those interrelations for manufacturing processes was my hope for this: https://www.kurtz-fernhout.com/oscomak/ https://www.kurtz-fernhout.com/oscomak/ https://www.oscomak.net/ https://www.oscomak.net/ https://openvirgle.net/ https://openvirgle.net/ And earlier, this: https://pdfernhout.net/princeton-graduate-school-plans.html https://pdfernhout.net/princeton-graduate-school-plans.html https://pdfernhout.net/sunrise-sustainable-technology-ventures.html https://pdfernhout.net/sunrise-sustainable-technology-ventur... Still think it is all a good idea. Glad the "maker" movement is making some progress in that area. As I noted on the LibrePlanet mailing list a few weeks ago: https://lists.gnu.org/archive/html/libreplanet-discuss/2022-01/msg00082.html https://lists.gnu.org/archive/html/libreplanet-discuss/2022-... Someday after I "retire" I hope to have more time to work on all that. Tangentially, on a super earth with more gravity, they would have an easier time going into orbit energetically using mass drivers or laser launch systems instead of rockets. And in any case, how big a seed do you really need to make a space infrastructure if you are patient? And the ground can communicate to space with radio or lasers (like for telepresence) which are not affected much by planetary gravity even for super earths.
• Animats 5y ago
  Everything is simply too far apart. That's very likely. There are only two known systems with possibly habitable planets within 40 light years.
  • brabel 5y ago
    Not to mention that when we talk about other galaxies, then distances are on a whole different scale again. While travelling to other stars takes "only" a few thousand years, to go to another galaxy you might need several hundred million years with any technology we can currently even imagine. Even if intelligent life is rare enough that it only appears once on a single galaxy every several billion years, we're still talking probably millions of possible civilizations, though each almost completely out-of-reach of each other.
    • pfdietz 5y ago
      We can achieve relativistic speeds with technologies we can imagine (specifically, laser light sails). This would require just millions of years to get to M-31, for example (which is 2 million light years away).
      • ncmncm 5y ago
        Arriving not in atomically finely tattered shreds is left as an exercise for the descendants. And, stopping.
        • pfdietz 5y ago
          They'd presumably do this starting from the fringes of the galaxy where the gas is thinner, and with a sufficiently big vehicle (perhaps assembled out of parts that are accelerated separately) that it could withstand some erosion. The sail itself would be discarded after acceleration. Drag on the interstellar medium using magnetic fields could be used for deceleration.
          • ncmncm 5y ago
• Arelius 5y ago
  What I don't see being brought up often.. So, the universe could be infinite right? Or at least many orders of magnitude larger than the "visible universe"? If that's the case, the occurance rate of life could be very very small, and we are still practically gaurenteed to exist, along with many (infinite) more life. But it's entirely possible that they are all over a "visible universe"'s distance away. Which with an expanding universe, would mean that we could never meet or even observe them. In some ways, that's maybe more lonely, or at least sad, than being entirely alone.
• dcvz234 5y ago
  Maybe we give ourself too much indulgency about how further we are in the technological evolution. Maybe we are just at caveman level +1 and looking for radio signals is like trying to find smoke based communications in NY. Maybe we are still missing something fundamental about the universe and we don't know, like we ignored electricity or nuclear forces existed just decades or 150 years ago. That UFO the US navy has in footage, from 2019, making a diving nose maybe at 200 mph into the ocean without making a single wave or splash, is telling you something: you don't know everything about physics, just yet.
  • wruza 5y ago
    But we can’t deny a natural barrier. Modern sci-tech if used in 18 century would dramatically explode into fundamental discoveries. Einstein Bohr et al would jump for joy having these “toys”, cause all they’ve had was basically pen and paper. But now sci-tech mostly supports existing theories for many decades. Not saying there is nothing new, but there is nothing groundbreaking either in fundamental parts of nature.
• rewgs 5y ago
  Yeah, I think that the Fermi Paradox can be pretty easily explained: the universe is fucking huge. Those who talk about the feasibility of alien life visiting us very simply haven't thought it through, or are ignorant of the reality of space. It's just too staggeringly big.
  • omnicognate 5y ago
    Yep, the Fermi "paradox" is no paradox at all. We have basically no evidence that life (including intelligent life) isn't common yet. There are so many ways to think of how big our galaxy is but two are particularly relevant to how difficult it would be to detect other life, or be detected: 1. The first radio signals the human race produced have so far travelled something like a thousandth of the distance to the other side of our galaxy. Light travels really slowly on astronomical scales. 2. A supernova goes off roughly once every 50 years in the milky way. That's an energy release that is utterly incomprehensible to a human being. A system-incinerating catastrophe briefly producing an energy output comparable to that of all the stars in the galaxy combined. But to us they appear as just brighter-than-usual dots in the sky. We (humans) have only noticed a handful of them. It's not that we're shielded from them. These events happen in direct line of sight. They're just insanely far way and light intensity falls off with the square of distance. The kinds of energy outputs produced by a species of comparable technology to our own are simply not visible to us over these kinds of distances, even with the very latest technology. And that's just our galaxy. If you consider the entire universe the things happening in direct line of sight include billion-solar-mass supermassive black hole mergers, and you need a gravitational wave detector to even tell they're happening. We've only just recently started to be able to detect the presence of planets around other stars. The Fermi Paradox, Great Filter, "Where's the intelligent life?" stuff is absurdly premature.
    • WillPostForFood 5y ago
      is absurdly premature. Only relative to our own existence. If the universe is ~14 billion years old, and life was plentiful, you might expect life to have emerged elsewhere hundreds of millions or a few billion years before us. That allows for enough time for signals to have reached earth, even at slow light speeds.
• Moodles 5y ago
  This is what I find most plausible as well. If we just look at facts we currently believe to be true, then we know there are enormous distances between planets and no fast way of travelling between them. Then for a lot of probabilities you want to assign to the likelihood of intelligent life emerging on a Goldilocks planet, the universe would look exactly like it does today. I.e. we’re all on isolated islands on a fast ocean, and it doesn’t matter how advanced our tech gets: we’re still all limited by the laws of physics so we all think we’re alone.
• GoblinSlayer 5y ago
  Also light is very slow. The Arecibo Message was sent in 1974, it's now 48 light years away, which is tiny.